Micro-electro-mechanical system (MEMS) variable capacitors and actuation components and related methods

ABSTRACT

Micro-electro-mechanical system (MEMS) variable capacitors and actuation components and related methods are provided. A MEMS variable capacitor can include first and second feed lines extending substantially parallel to one another. Further, MEMS variable capacitors can include first and second capacitive plates being spaced apart from the first and second feed lines. The first and second capacitive plates can be separately movable with respect to at least one of the first and second feed lines for varying the capacitance between the first and second feed lines over a predetermined capacitance range.

RELATED APPLICATIONS

The presently disclosed subject matter claims the benefit of U.S.Provisional Patent Application Ser. No. 60/780,565, filed Mar. 8, 2006,the disclosure of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to MEMScomponents. More particularly, the subject matter disclosed hereinrelates to MEMS variable capacitors and actuation components andmethods.

BACKGROUND

MEMS have been shown to be useful for a variety of consumer, industrialand military applications. Most MEMS devices are fabricated onsemiconductor substrates (e.g., silicon, Gallium Arsenide,Silicon-On-Insulator, etc.) using standard Integrated Circuit (IC)processes in combination with specialized micromachining processes.Collectively these manufacturing technologies are frequently calledmicrofabrication processes.

Recently there has been a large interest in making MEMS Radio Frequency(RF) devices and systems for a variety of high volume communicationapplications. MEMS-based RF components and systems have typically beenrealized on traditional semiconductor materials, primarily siliconwafers, due to the high quality of the materials and processes developedover the years and due to the expectation of direct monolithicintegration of the MEMS with integrated circuits. This approach hasseveral disadvantages for the performance and potentialcommercialization of RF and microwave devices. In particular, thedielectric losses of the silicon substrate are very high at frequenciesabove 1 GHz and high metallization sheet resistances. Further, such MEMScomponents can produce RF interference into underlying and surroundingcircuitry and vice versa.

There is also a benefit in producing MEMS variable capacitors that meetcertain performance requirements. For example, there is a desire toprovide MEMS variable capacitors having high quality factor (Q) over arange of different frequencies. Also, there is a desire to provide MEMSvariable capacitors with improved capacitance ratio (the ratio ofminimum to maximum capacitance of a variable capacitor). The capacitanceratio may be achieved by providing variable capacitors with a minimizedparasitic fixed capacitance and maximized capacitance in the highcapacitance state. It is also desired to highly isolate the RF portionsof the MEMS circuits from the substrate noise and losses.

In view of the foregoing, it is desired to provide improved MEMSvariable capacitors and actuation components and methods.

SUMMARY

In accordance with this disclosure, novel MEMS variable capacitors andactuation components and related methods are provided.

It is an object of the present disclosure therefore to provide novelMEMS variable capacitors and actuation components and related methods.This and other objects as may become apparent from the presentdisclosure are achieved, at least in whole or in part, by the subjectmatter described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter described herein will now be explained with referenceto the accompanying drawings of which:

FIGS. 1A-1F are different views of a MEMS variable capacitor accordingto one embodiment of the subject matter described herein;

FIG. 2 is a top perspective view of a MEMS variable capacitor accordingto one embodiment of the subject matter described herein;

FIGS. 3A-3C are different views of a MEMS variable capacitor accordingto one embodiment of the subject matter described herein;

FIG. 4 is a top view of a MEMS variable capacitor having feed linesextending substantially parallel to one another according to anembodiment of the subject matter described herein;

FIG. 5 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines connected to alternating feed padsaccording to an embodiment of the subject matter described herein;

FIG. 6A is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 6B is a top view of a MEMS variable capacitor system having doublesets of cantilever-type variable capacitors and feed lines according toan embodiment of the subject matter described herein;

FIG. 6C is a top view of another MEMS variable capacitor system havingdouble sets of cantilever-type variable capacitors and feed linesaccording to an embodiment of the subject matter described herein;

FIG. 7 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 8A is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 8B is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 9 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 10 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 11 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 12 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 13 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 14 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIG. 15 is a top view of a MEMS variable capacitor system having MEMSvariable capacitors and feed lines according to an embodiment of thesubject matter described herein;

FIGS. 16A and 16B are a top view and a perspective view, respectively,of a MEMS variable capacitor having a shielding according to anembodiment of the subject matter described herein;

FIG. 16C is a perspective view of a MEMS variable capacitor having acontoured shielding according to an embodiment of the subject matterdescribed herein;

FIGS. 17A-17E are graphs illustrating simulation results of thecapacitor system shown in FIG. 5;

FIGS. 18A-18D are graphs illustrating simulation results of thecapacitor system shown in FIG. 6;

FIGS. 19A-19E are graphs illustrating simulation results of thecapacitor system shown in FIG. 7;

FIG. 20 is a graph illustrating simulation results of the capacitorsystem shown in FIG. 11;

FIG. 21 is a graph illustrating simulation results of the capacitorsystem shown in FIG. 15;

FIG. 22 is a graph illustrating simulation results of the capacitorsystem shown in FIG. 12;

FIGS. 23A and 23B are graphs illustrating simulation results of thecapacitor system shown in FIG. 13; and

FIG. 24 is a graph illustrating simulation results of the capacitorsystem shown in FIG. 14.

DETAILED DESCRIPTION

In accordance with the present disclosure, MEMS variable capacitors andactuation components and related methods are provided. The MEMS variablecapacitors and actuation components and methods described herein canhave particular application for use in MEMS RF devices, systems andmethods for a variety of high volume communication applications. Thesubject matter described herein can be applied for reducing dielectriclosses, improving Q, improving capacitance ratio, and improvingsubstrate and circuit isolation.

MEMS Variable Capacitors and Actuation Components

In one embodiment, a MEMS actuation component or variable capacitor caninclude first and second actuation electrodes being spaced apart,wherein at least one of the actuation electrodes being movable withrespect to the other actuation electrode. Further, the MEMS actuationcomponent or variable capacitor can include a movable component attachedto the at least one of the actuation electrodes. The movable componentcan comprise a movable end and a stationary end. The movable end can bemovable when a voltage is applied across the first and second actuationelectrodes, and wherein the stationary end comprises at least tworesilient arms for providing resistance to movement of the movable endwhen the voltage is applied. One exemplary advantage of the resilientarms is that “snap-in” voltage can be reduced as a result of increasedcontrol of resistance to the movement of the movable end when thevoltage is applied.

FIGS. 1A-1F illustrate different views of a MEMS variable capacitorgenerally designated 100 according to one embodiment of the subjectmatter described herein. Alternative to being a variable capacitor, theMEMS variable capacitors shown and described herein can generally be aMEMS actuation component without capacitance functionality. Such MEMSactuation components can be used in any suitable application foreffecting movement. FIGS. 1A-2 represent “cantilever-type” variablecapacitors. Generally, cantilever-type variable capacitors include amovable component having a single stationary end about which the movablecomponent moves.

FIG. 1A is a cross-sectional front view of variable capacitor 100 in aclosed position. Referring to FIG. 1A, variable capacitor 100 caninclude first and second capacitive elements CE1 and CE2 disposed on asurface of a dielectric layer DE. Capacitive elements CE1 and CE2 can beconnected to feed lines FL1 and FL2, respectively. In one example,capacitive elements as described herein can be a feed line extendingalong the top surface of dielectric layer DE. Alternatively, capacitiveelements can be a capacitive plate or any other suitable conductivematerial shaped and sized for forming capacitance with another nearbyconductive material. Feed lines described herein can be between about 10μm to about 200 μm wide or any other suitable dimension. Further, feedlines described herein can be spaced by about 5 μm to about 50 μm or anyother suitable spacing.

Feed lines FL1 and FL2 can be connected to a signal line SL. A firstcapacitive plate CP1 can be positioned on an opposing side of an air gapAG from capacitive elements CE1 and CE2 to form a capacitance acrossfeed lines FL1 and FL2. First capacitive plate CP1 can be spaced fromcapacitive elements CE1 and CE2 by a distance d1 in the closed position.The distance between plate CP1 and capacitive elements CE1 and CE2 canfor example be about 0.5 to 4 microns. FIG. 1B is a cross-sectionalfront view of variable capacitor 100 in an open position, wherein firstcapacitive plate CP1 can be spaced from capacitive elements CE1 and CE2by a distance d2. Variable capacitor 100 can include bumps B forpreventing capacitive plate CP1 from contacting capacitive elements CE1and/or CE2. Bumps can be in any number and placed in any suitablepositioned on a bottom surface of a movable component for preventing theundesired contact of components. In one example, bumps can be locatednear capacitive plates. In another example, bumps can be located nearactuation electrodes.

In one embodiment, variable capacitor 100 does not include bumps B asshown in FIGS. 1A-1C. In this embodiment, actuation electrodes AE2 andAE3 can contact. One or both of the contacting surfaces of actuationelectrodes AE2 and AE3 can include a dielectric (or other suitableinsulator) for preventing the electrical conduction (shorting) betweenactuation electrodes AE2 and AE3. This can be advantageous, for example,for achieving the largest value capacitors.

FIG. 1C is a top perspective view of variable capacitor 100. Referringto FIG. 1C, the capacitance of variable capacitor 100 can be varied byapplying varying voltage across actuation electrodes AE1 and AE2. Whenvoltage is applied across actuation electrodes AE1 and AE2, a movableend ME of a movable component MC can deflect towards substrate S while astationary end SE remains stationary due to its attachment to dielectricDE and substrate S. As a result of the deflection, the distance betweencapacitive plates CP1 and CP2 and capacitive elements CE1 and CE2narrows, and therefore, the capacitance changes. Variable capacitor 100can also include an actuation electrode (not shown) on an opposing sideof movable component MC from actuation electrode AE1 and electricallyconnected to actuation electrode AE1 for deflecting movable end MEtowards substrate S on application of the voltage. This operation willbe continuous over a range of actuation voltage and then has adiscontinuous jump to a larger capacitance as “pull-in” is achieved.Both modes of operation may be advantageous.

In one embodiment, variable capacitor 100 can be fabricated on asubstrate S and dielectric DE. In particular, for example, feed linesFL1 and FL2 can be buried within substrate S and/or dielectric DE andinclude ends that extend to a surface of dielectric DE. A conductivelayer can be deposited over the top surface of dielectric DE and theends of feed lines FL1 and FL2. The conductive layer can be etched toform capacitive elements CE1 and CE2 on the ends of feed lines FL1 andFL2, respectively. Further, the conductive layer can be etched to formactuation electrodes AE2. Alternatively, actuation electrode AE2 can beformed by lift-off or other patterning processes known by those of skillin the art.

A sacrificial layer can be deposited on capacitive elements CE1 and CE2and dielectric DE. Next, apertures A1 and A2 can be etched in thesacrificial layer through to the surface of dielectric DE. Movablecomponent MC can be formed by depositing a layer of oxide on capacitiveplate CP1, the sacrificial layer, and in apertures A1 and A2 through tothe surface of dielectric DE. The sacrificial layer can be removed toform an air gap between capacitive plate CP1 and capacitive elements CE1and CE2. The air gap can be varied to achieve different capacitances.Further, a conductive layer can be formed on movable component MC andthe conductive layer etched to form a second capacitive plate CP2.Exemplary materials for actuation electrodes AE1 and AE2 include metal,semi-metal, doped semiconductor, and combinations thereof. Exemplarymaterials for movable component MC includes silica, alumina, un-dopedsemiconductors, polymers, metals, semi-metals, doped semi-conductors,and combinations thereof.

FIG. 1D is a top view of variable capacitor 100. Stationary end SEincludes resilient arms RA1 and RA2, which can bend and resist thedeflection of movable end ME towards substrate S when voltage is appliedacross the actuation electrodes. A notched portion N provides spacingbetween resilient arms RA1 and RA2. The thickness of resilient arms RA1and RA2 can be varied for increasing or decreasing their resistance tothe deflection of movable end ME. Further, the length of resilient armsRA1 and RA2 can be made longer or shorter for increasing or decreasing,respectively, resistance to the deflection of movable end ME. Resilientarms RA1 and RA2 can have at least one of a predefined dimension andsize for providing a predetermined resistance to the movement of themovable end such that the movable end is a predetermined distance fromsubstrate S when a predetermined voltage is applied across first andsecond actuation electrodes AE1 and AE2. In one embodiment, resilientarms RA1 and RA2 are substantially parallel to one another. Further,resilient arms RA1 and RA2 can have at least one of a predefineddimension and size for providing a predetermined resistance to themovement of movable end ME such that capacitive plates CP1 and CP2 are apredetermined distance from capacitive elements CE1 and CE2 when apredetermined voltage is applied across first and second actuationelectrodes AE1 and AE2.

FIG. 1E is a side view of MEMS variable capacitor 100. Variablecapacitor 100 can include an actuation electrode AE3 in electricalcommunication with actuation AE1. A voltage can be applied across secondactuation electrode AE2 and first/third actuation electrodes AE1/AE3 formoving movable component MC.

FIG. 1F is another top view of MEMS variable capacitor 100. In thisview, actuation electrode AE1 and capacitive plate CP2 are now shown inorder to provide a better view of actuation electrode AE3 and capacitiveplate CP1 (indicated by broken lines) attached to an underside ofmovable component MC. Actuation electrode AE3 and capacitive plate CP1can be electrically connected.

FIG. 2 is a top perspective view of a MEMS variable capacitor generallydesignated 200 according to one embodiment of the subject matterdescribed herein. Referring to FIG. 2, variable capacitor 200 can besimilar to variable capacitor 100 shown in FIG. 1 except for thearrangement of capacitive elements CE1 and CE2 and capacitive plates CP1and CP2. In particular, capacitive elements CE1 and CE2 can be alignedwith one another along the length of movable component. Further,capacitive plates CP1 (not shown) and CP2 can be extended in length suchthat they are positioned over capacitive elements CE1 and CE2.

In one embodiment, a MEMS variable capacitor or actuation component caninclude first and second actuation electrodes being spaced apart. Atleast one of the actuation electrodes can be movable with respect to theother actuation electrode. A movable component can be attached to thefirst actuation electrode. The movable component can comprise a movableportion and first and second stationary ends. The movable portion can bemovable when a voltage is applied across the first and second actuationelectrodes. The stationary ends can each comprise at least two resilientarms for providing resistance to movement of the movable component whenthe voltage is applied.

FIGS. 3A-3C illustrate different views of a MEMS variable capacitorgenerally designated 300 according to one embodiment of the subjectmatter described herein. FIGS. 3A and 3B represent “bridge-type”variable capacitors. Generally, bridge-type variable capacitors includea movable component having at least two stationary ends about which amovable portion of the movable component moves.

FIG. 3A is a cross-sectional side view of variable capacitor 300.Referring to FIG. 3A, variable capacitor 300 can include first andsecond capacitive elements CE1 and CE2 disposed on a surface of asubstrate S. Capacitive elements CE1 and CE2 can be connected to feedlines FL1 and FL2, respectively. Feed lines FL1 and FL2 can be connectedto signal line SL. First capacitive plate CP1 can be positioned on anopposing side of an air gap AG from capacitive elements CE1 and CE2 toform a capacitance across feed lines FL1 and FL2.

The capacitance of variable capacitor 300 can be varied by applyingvarying voltage across actuation electrodes. In particular, capacitor300 can include actuation electrodes AE1, AE2, AE3, and AE4 positionedon movable component. Further, actuation electrodes AE5 and AE6 can bepositioned on a top surface of substrate S. A voltage difference can beapplied between actuation electrode AE5 and AE1 and AE2. Further, avoltage difference can be applied between actuation electrode AE6 andAE3 and AE4. At a sufficiently high voltage difference, a center portionof a movable component MC (the portion at which capacitive plates CP1and CP2 are attached) can deflect towards substrate S while stationaryends SE1 and SE2 remain stationary due to their attachment to substrateS. As a result of the deflection, the distance between capacitive platesCP1 and CP2 and capacitive elements CE1 and CE2 narrows, and therefore,the capacitance changes. Pull-in can occur at greater than a thresholdvoltage such that the capacitor value jumps and becomes stabilized.

In one embodiment, variable capacitor 300 can be fabricated on asubstrate S. In particular, for example, feed lines FL1 and FL2 can beburied within substrate S and include ends that extend to a surface ofsubstrate S. A conductive layer can be deposited over the top surface ofsubstrate S and the ends of feed lines FL1 and FL2. The conductive layercan be etched to form capacitive elements CE1 and CE2 on the ends offeed lines FL1 and FL2, respectively. Further, the conductive layer canbe etched to form actuation electrodes AE5 and AE6.

A sacrificial layer can be deposited on capacitive elements CE1 and CE2,substrate S, and actuation electrodes AE5 and AE6. Next, apertures canbe etched in the sacrificial layer through to the surface of substrateS. Movable component MC can be formed by depositing a layer of oxide oncapacitive plates CP1 and CP2, the sacrificial layer, actuationelectrode AE5 and AE6, and in the apertures A1 and A2 through to thesurface of substrate S. The sacrificial layer can be removed to form anair gap between capacitive plates CP1 and CP2 and capacitive elementsCE1 and CE2. The air gap can be varied to achieve differentcapacitances. Further, a conductive layer can be formed on movablecomponent MC and the conductive layer etched to form a second capacitiveplate CP2.

FIG. 3B is a top view of variable capacitor 300. Variable capacitor 300can include station ends SE1 and SE2. Stationary ends SE1 and SE2 caneach include resilient arms RA1 and RA2, which can bend and resist thedeflection of movable end ME towards substrate S when voltage is appliedacross the actuation electrodes. A notched portion N provides spacingbetween resilient arms RA1 and RA2. The thickness of resilient arms RA1and RA2 can be varied for increasing or decreasing their resistance tothe deflection of movable end ME. Further, the length of resilient armsRA1 and RA2 can be made longer or shorter for increasing or decreasing,respectively, resistance to the deflection of movable end ME. Resilientarms RA1 and RA1 can have at least one of a predefined dimension andsize for providing a predetermined resistance to the movement of amovable portion MP such that capacitive plates CP1 and CP2 are apredetermined distance from capacitive elements CE1 and CE2 when apredetermined voltage is applied across the actuation electrodes. FIG.3C is a perspective view of MEMS variable capacitor 300.

In one embodiment, a plurality of MEMS variable capacitors as describedabove can be spaced apart from substantially parallel feed lines forvarying capacitance between the feed lines over a predeterminedcapacitance range. This arrangement can result in a reduction insubstrate surface area required for implementing the variable capacitor.In particular, a MEMS variable capacitor according to the subject matterdescribed herein can include first and second feed lines extendingsubstantially parallel to one another. Further, the MEMS variablecapacitor can include first and second capacitive plates being spacedapart from the first and second feed lines. The first and secondcapacitive plate can be separately movable with respect to at least oneof the first and second feed lines for varying the capacitance betweenthe first and second feed lines over a predetermined capacitance range.

MEMS Variable Capacitors and Variable Capacitor Systems

In one embodiment, a MEMS variable capacitor can include first andsecond feed lines extending substantially parallel to one another. Thevariable capacitor can also include first and second capacitive platesspaced apart from the first and second feed lines. The first and secondcapacitive plates can be separately movable with respect to at least oneof the first and second feed lines for varying the capacitance betweenthe first and second feed lines over a predetermined capacitance range.

It can be advantageous to include a maximum number of capacitiveelements while minimizing the length of its feed network in order toreduce feed resistance and maximize Q for a given capacitance. It isalso advantageous to achieve a desired capacitance range with a givennumber of MEMS variable capacitance while minimizing the number/amountof feed lines and feed pads required to achieve the desired capacitancerange to maximize area usage and minimize parasitic capacitance. This isone exemplary objective of the examples provided hereinbelow.

FIG. 4 is a top view of MEMS variable capacitor generally designated 400having feed lines extending substantially parallel to one anotheraccording to an embodiment of the subject matter described herein.Referring to FIG. 4, variable capacitor 400 can include feed lines FL1and FL2 extending substantially parallel to one another. In thisexample, feed lines FL1 and FL2 are attached to pads P1 and P2,respectively, on a top surface of substrate SS. Feed lines FL1 and FL2can be positioned on substrate surface SS or can be in whole or in partburied beneath substrate surface SS. Feed pads P1 and P2 can beconnected to a signal line.

Variable capacitor 400 can include a plurality of capacitive plates CP1,CP2, CP3, and CP4 spaced apart from feed lines FL1 and FL2 in an atleast substantially perpendicular direction with respect to substratesurface SS. Capacitive plates CP1, CP2, CP3, and CP4 can be separatelymovable with respect to at least one of feed lines FL1 and FL2 forvarying the capacitance between feed lines FL1 and FL2 over apredetermined capacitance range. In particular, capacitive plates CP1,CP2, CP3, and CP4 can be separately movable in a substantially verticaldirection with respect to substrate surface SS by actuation of variablecapacitors VC1, VC2, VC3, and VC4, respectively.

In FIG. 4, there are four variable capacitors VC1, VC2, VC3, and VC4.Alternatively, there can be any suitable number of variable capacitorsacross feed lines FL1 and FL2 (e.g., 1 or 2 variables capacitors). Thefeed line length can be reduced or lengthened depending on the variablecapacitor size in order to minimize the area required by all of thecomponents.

Variable capacitors VC1, VC2, VC3, and VC4 can be similar to actuationcomponent 200 shown in FIG. 2. In particular, variable capacitors VC1,VC2, VC3, and VC4 can include actuation electrodes AE1, AE2, AE3, andAE4, respectively, and corresponding actuation electrodes attached tosubstrate surface SS. Movement of variable capacitors VC1, VC2, VC3, andVC4 can be effected by application of a voltage across actuationelectrodes AE1, AE2, AE3, and AE4, respectively, and a correspondingactuation electrode attached to substrate surface SS. By controlling themovement of variable capacitors VC1, VC2, VC3, and VC4, capacitiveplates CP1, CP2, CP3, and CP4 can be separately movable with respect toat least one of feed lines FL1 and FL2 for varying the capacitancebetween feed lines FL1 and FL2 over a predetermined capacitance range.

In one embodiment, variable capacitors VC1, VC2, VC3, and VC4 can eachbe substituted with variable capacitor 300 shown in FIG. 3. In thisembodiment, variable capacitor 300 can form a “bridge” over feed linesFL1 and FL2 such that capacitive plates CP1 and CP2 are positioned overfeed lines FL1 and FL2. By controlling the movement of the variablecapacitors, capacitive plates CP1 and CP2 can be moved with respect tofeed lines FL1 and FL2 for varying the capacitance between feed linesFL1 and FL2 over a predetermined capacitance range.

In one embodiment, a MEMS variable capacitor system can include variablecapacitors as described above connected to alternating feed pads. Thisarrangement can result in a reduction in substrate surface area requiredfor implementing the variable capacitor. A MEMS variable capacitorsystem according to an embodiment of the subject matter described hereincan include first, second, and third feed pads being spaced apart. Inone example, the feed pads can be aligned along a substrate surface in asubstantially straight line. Further, MEMS variable capacitors and feedlines can be positioned between the feed pads.

The first feed line can be connected to a first feed pad and extendtowards a second feed pad. A second feed line can be connected to thesecond feed pad and extend towards the second feed pad. Third and fourthfeed lines can be connected to the third feed pad and extend towards thefirst and second feed pads, respectively. A first capacitive plate canbe spaced apart from the first and third feed lines. The firstcapacitive plate can be movable with respect to at least one of thefirst and third feed lines for varying the capacitance between the firstand third feed lines over a predetermined capacitance range. A secondcapacitive plate can be spaced apart from the second and fourth feedlines. The second capacitive plate can be movable with respect to atleast one of the second and fourth feed lines for varying thecapacitance between the second and fourth feed lines over a secondpredetermined capacitance range. In one example, a MEMS variablecapacitor as described herein can be connected to a capacitive plate formoving the capacitive plate with respect to at least one feed line.

In one embodiment, a MEMS variable capacitor system can include first,second, and third feed pads being spaced apart. A first feed line can beconnected to the first feed pad and extending towards the third feedpad. A second feed line can be connected to the second feed pad andextending towards the third feed pad. Third and fourth feed linesconnected to the third feed pad and extending towards the first andsecond feed pads, respectively. A first capacitive plate can be spacedapart from the first and third feed lines. The first capacitive platecan be movable with respect to at least one of the first and third feedlines for varying the capacitance between the first and third feed linesover a first predetermined capacitance range. A second capacitive platecan be spaced apart from the second and fourth feed lines. The secondcapacitive plate can be movable with respect to at least one of thesecond and fourth feed lines for varying the capacitance between thesecond and fourth feed lines over a second predetermined capacitancerange.

FIG. 5 is a top view of a MEMS variable capacitor system generallydesignated 500 having MEMS variable capacitors and feed lines connectedto alternating feed pads according to an embodiment of the subjectmatter described herein. Referring to FIG. 5, system 500 can includevariable capacitors 502 and 504 where each can include a plurality ofvariable capacitors 300. Variable capacitors 300 can each includeactuation electrodes AE1 and AE2. Voltage can be applied acrossactuation electrodes AE1 and AE2 and respective variable capacitorsattached to substrate surface SS for movement of variable capacitors 300with respect to substrate surface SS.

Capacitive plates CP2 of capacitor 500 can be spaced apart from feedlines F1 and F2. On application of voltage for movement of variablecapacitors 300, capacitive plates CP2 of capacitor 500 can move withrespect to at least one of feed lines F1 and F2 for varying thecapacitance between feed lines FL1 and FL2 over a predeterminedcapacitance range. Similarly, voltage can be applied to variablecapacitors 300 of capacitor 502 for varying the capacitance between feedlines FL3 and FL4 positioned below capacitive plates CP2.

System 500 can include feed pads PD1, PD2, and PD3 that are spaced apartand connected to signal lines. In particular, feed pads PD1 and PD2 canbe connected to a signal line. Feed pads PD2 and PD3 can be connected toanother signal line. Feed line F1 can be connected to feed pad PD1 andextend towards feed pad PD2. Feed line F3 can be connected to feed padPD3 and extend towards feed pad PD2. Feed lines F2 and F4 can beconnected to feed pad PD2 and extend towards feed pads PD1 and PD3,respectively. Feed lines F1 and F2 can be substantially parallel to oneanother. Feed lines F3 and F4 can be substantially parallel to oneanother. The variable capacitors can be individually controlled forselectively varying the capacitance.

In one embodiment, variable capacitors 300 can each be substituted withvariable capacitor 200 shown in FIG. 2. In this embodiment, capacitanceplate CP2 of variable capacitor 100 can be positioned over the feedlines. By controlling the movement of the variable capacitors,capacitive plate CP2 can be moved with respect to respective feed linesfor varying the capacitance between the feed lines over a predeterminedcapacitance range. The variable capacitors can be individuallycontrolled for selectively varying the capacitance.

Individual element capacitance can vary between 1 fF and 10 pF witharrays used to build up larger total capacitance values. The values ofcapacitance elements in an array may not all be the same. For example,the capacitor head cross a pair of feed lines can have different widths.Scaling the actuator properly with the capacitor can yield the sameactuation voltage but the different capacitor head width can provide adifferent capacitance. For example, it may be advantageous to have abinary sequence of capacitance values where the capacitor head widthsvary proportional to powers of 2. The capacitor electrodes can havedimensions in either direction from 1 micron to 200 microns. Theelectrodes can be made from a highly conductive material such as a metalor semi-metal. The feed line widths can be sized in combination with thecapacitor electrode to determine the capacitance and may be between 5microns and 200 microns. The feed line length is set the minimumrequired to feed all the capacitors in the array. As more elements areadded to a given array fed by a set of pads, the Q will be reduced. Atthe other extreme of one MEMS capacitor per pad, pad parasitics willlimit the performance. Thus, there is an optimum number of MEMS elementsper set of pads that is design specific but will typically range from 2to 8. Note that more elements can be added by paralleling multiplearrays as is shown in the several of the figures. This paralleling canalso be done the circuit to which the capacitor array is connected. Theoperation voltage of the actuators is between 3 and 150V with valuesnear 40V preferable due to the balance of actuator area usage andvoltage capabilities of readily available commercial CMOS controlcircuitry.

FIG. 6A is a top view of a MEMS variable capacitor system generallydesignated 600 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 6A, system 600 can include variable capacitors generally designated602, 604, and 606. Variable capacitor 602 can include variablecapacitors VC1, VC2, VC3, and VC4 positioned above feed lines FL1, FL2,FL3, and FL4. In particular, capacitive plates CP of variable capacitorsVC1 and VC2 can be disposed over feed lines FL1 and FL3. Further,capacitive plates CP of variable capacitors VC3 and VC4 can be disposedover feed lines FL2 and FL4. The capacitive plates can be spaced apartfrom the feed lines in an at least substantially perpendicular directionwith respect to substrate surface SS. Feed lines FL1 and FL2 can beconnected to feed pad P1. Feed lines FL3 and FL4 can be connected tofeed pad P2. Feed pads P1 and P2 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed lines FL1 and FL3 and feed lines FL2 andFL4 are selectively varied.

Variable capacitor 604 can include variable capacitors VC5 and VC6having capacitive plates CP positioned above feed lines FL5 and FL6.Capacitive plates CP of variable capacitors VC5 and VC6 can beseparately moved by application of voltages to variable capacitors VC5and VC6 for movement of components VC5 and VC6 such that the capacitancebetween feed lines FL5 and FL6 is selectively varied. Feed lines FL5 andFL6 can be connected to feed pads P3 and P4, respectively. Feed pads P3and P4 can be connected to a signal line.

Variable capacitor 606 can include variable capacitors VC7 and VC8having capacitive plates CP positioned above feed lines FL7 and FL8.Capacitive plates CP of variable capacitors VC7 and VC8 can beseparately moved by application of voltages to variable capacitors VC7and VC8 for movement of components VC7 and VC8 such that the capacitancebetween feed lines FL7 and FL8 is selectively varied. Feed lines FL7 andFL8 can be connected to feed pads P5 and P6, respectively. Feed pads P5and P6 can be connected to a signal line.

As set forth above, it can be advantageous to include a maximum numberof capacitive elements as compared to the length of its feed network inorder to maximize Q for a given capacitance. In an example of modifyingthe embodiment described with respect to FIG. 6A for providing a “2 bit”variable capacitor, a variable capacitor may only include variablecapacitors VC2 and VC3, feedlines FL1-FL4 extending only under variablecapacitors VC2 and VC3 to an outer edge of the variable capacitors, andfeed pads P1 and P2. Variable capacitors VC2 and VC3 can be controllablyactivated for providing a “2 bit” variable capacitor. In this example, amaximum number of capacitive elements (i.e., 2) is provided as comparedto its feed network in order to maximize Q for a given capacitancerange.

In this example, the variable capacitors are “bridge” variablecapacitors as shown in FIGS. 3A and 3B. Alternatively, the variablecapacitors can be “cantilever-type” variable capacitors as shown in FIG.2. FIG. 6B is a top view of a MEMS variable capacitor system generallydesignated 608 having double sets of cantilever-type variable capacitorsand feed lines according to an embodiment of the subject matterdescribed herein. Referring to FIG. 6B, system 608 can include aplurality of variable capacitors generally designated 610, 612, 614,616, 618, and 620 having a plurality of cantilever-type variablecapacitors 200. Variable capacitors 200 can include capacitive platesCP. Variable capacitors 610 and 612 share a common feed pad PD1.Variable capacitors 614 and 616 share a common feed pad PD2. Variablecapacitors 618 and 620 can share a common feed pad PD3.

Variable capacitors 200 of variable capacitor 610 can be positioned overfeed lines FL1 and FL2. Feed line FL1 can be connected to a feed padPD4. Feed pads PD1 and PD4 can be connected to a signal line. variablecapacitors 200 of capacitors 610 can be separately activated for varyingthe capacitance between feeds lines FL1 and FL2.

Variable capacitors 200 of variable capacitor 612 can be positioned overfeed lines FL3 and FL4. Feed lines FL3 and FL4 can be connected to feedpads PD1 and PD5, respectively. Feed pads PD1 and PD5 can be connectedto a signal line. Variable capacitors 200 of capacitors 612 can beseparately activated for varying the capacitance between feeds lines FL3and FL4.

Variable capacitors 200 of variable capacitor 614 can be positioned overfeed lines FL6, FL7, FL8, and FL9. Feed lines FL6 and FL7 can beconnected to a feed pad PD6. Feed lines FL8 and FL9 can be connected tofeed pad PD2. Feed pads PD2 and PD6 can be connected to a signal line.Variable capacitors 200 of capacitors 614 can be separately activatedfor varying the capacitance between feeds lines FL6/FL7 and FL8/FL9.

Variable capacitors 200 of variable capacitor 616 can be positioned overfeed lines FL10, FL11, FL12, and FL13. Feed lines FL10 and FL11 can beconnected to a feed pad PD2. Feed lines FL12 and FL13 can be connectedto a feed pad PD7. Feed pads PD2 and PD7 can be connected to a signalline. Variable capacitors 200 of capacitors 616 can be separatelyactivated for varying the capacitance between feeds lines FL10/FL11 andFL12/FL13.

Variable capacitors 200 of variable capacitor 618 can be positioned overfeed lines FL14 and FL15. Feed line FL14 can be connected to a feed padPD8. Feed line FL15 is connected to feed pad PD3. Feed pads PD3 and PD8can be connected to a signal line. Variable capacitors 200 of capacitors618 can be separately activated for varying the capacitance betweenfeeds lines FL14 and FL15.

Variable capacitors 200 of variable capacitor 620 can be positioned overfeed lines FL16 and FL17. Feed line FL16 can be connected to feed padPD3. Feed line FL17 can be connected to a feed pad PD9. Feed pads PD3and PD9 can be connected to a signal line. Variable capacitors 200 ofcapacitors 620 can be separately activated for varying the capacitancebetween feeds lines FL16 and FL17.

FIG. 6B is a top view of another MEMS variable capacitor system havingdouble sets of cantilever-type variable capacitors and feed linesaccording to an embodiment of the subject matter described herein. Thissystem is similar to the system shown in FIG. 6B except the feed linesare not connected between variable capacitors VC1 and VC6 as shown.Further, the feed lines are not connected between variable capacitorsVC4 and VC7 as shown. In this example, the variable capacitorspositioned above respective feed lines can function together as a singlecapacitor for effecting capacitance change at respective feed pads.Additionally, shielding material (as described below with respect to theexamples of FIGS. 16A-16C) can be provided in a substrate beneath thesecomponents for providing the functionality described hereinbelow withrespect to shielding.

In one embodiment, a MEMS variable capacitor system can include a commonfeed line being surrounded by a plurality of other feed lines forvarying the capacitance between the common feed line with respect to theother feed lines. In particular a MEMS variable capacitor according toone embodiment of the subject matter described herein can include afirst feed line between positioned on a first defined area. A pluralityof second feed lines can be positioned on a plurality of second definedareas that can at least substantially surround the first defined area. Aplurality of capacitive plates can each be spaced apart from the firstfeed line. Further, each of the capacitive plates can be spaced apartfrom a respective one of the second feed lines. Each of the capacitiveplates can be separately movable with respect to the first feed line andthe respective one of the second feed lines for varying the capacitancebetween the first feed line and the respective one of the second feedlines over a predetermined capacitance range.

In one embodiment, a MEMS variable capacitor can include a first feedline being positioned on a first defined area. A plurality of secondfeed lines can be positioned on a plurality of second defined areas thatsubstantially surround the first defined area. A plurality of capacitiveplates can each be spaced apart from the first feed line. Further, eachof the capacitive plates can be spaced apart from a respective one ofthe second feed lines. Each of the capacitive plates can be separatelymovable with respect to the first feed line and the respective one ofthe second feed lines for varying the capacitance between the first feedline and the respective one of the second feed lines over apredetermined capacitance range.

FIG. 7 is a top view of a MEMS variable capacitor system generallydesignated 700 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 7, system 700 can include variable capacitors generally designated702, 704, 706, and 708. Variable capacitor system 700 can includecantilever-type variable capacitors 710-732 positioned over feed linesFL1-FL9. In particular, capacitive plate CP of variable capacitors 710is positioned overfeed lines FL2 and FL9. Capacitive plate CP ofvariable capacitors 712 and 714 are positioned over feed lines FL1 andFL9. The capacitive plates can be spaced apart from the feed lines in anat least substantially perpendicular direction with respect to substratesurface SS. Feed line FL9 can be connected to feed pad P1. Feed linesFL1 and FL2 can be connected to feed pad P2. Feed pads P1 and P2 can beconnected to a signal line. The capacitive plates can be separatelymoved by application of voltages to variable capacitors 710, 712, and714 for movement of the variable capacitors such that the capacitancesbetween feed lines FL1 and FL9 and feed lines FL2 and FL9 areselectively varied.

Variable capacitor 704 can include variable capacitors 716, 718, and 720having capacitive plates CP positioned above feed lines FL3, FL4 andFL9. Capacitive plates CP of variable capacitor 716, 718, and 720 can beseparately moved by application of voltages to variable capacitors 716,718, and 720 for movement of components 716, 718, and 720 such that thecapacitances between feed line FL9 and feed lines FL3 and FL4 areselectively varied. Feed lines FL3 and FL4 can be connected to feed padP3. Feed pads P1 and P3 can be connected to a signal line.

Variable capacitor 706 can include variable capacitors 722, 724, and 726having capacitive plates CP positioned above feed lines FL5, FL6 andFL9. Capacitive plates CP of variable capacitors 722, 724, and 726 canbe separately moved by application of voltages to variable capacitors722, 724, and 726 for movement of components 722, 724, and 726 such thatthe capacitances between feed line FL9 and feed lines FL5 and FL6 areselectively varied. Feed lines FL5 and FL6 can be connected to feed padP4. Feed pads P1 and P4 can be connected to a signal line.

Variable capacitor 708 can include variable capacitors 728, 730, and 732having capacitive plates CP positioned above feed lines FL7, FL8 andFL9. Capacitive plates CP of variable capacitors 728, 730, and 732 canbe separately moved by application of voltages to variable capacitors728, 730, and 732 for movement of components 728, 730, and 732 such thatthe capacitances between feed line FL9 and feed lines FL7 and FL8 areselectively varied. Feed lines FL7 and FL8 can be connected to feed padP5. Feed pads P1 and P5 can be connected to a signal line.

In the example of system 700, feed line FL9 is positioned on a definedarea of substrate surface SS. Feed lines FL1-FL8 are positioned on aplurality of other defined areas of substrate surface SS. The definedareas of feed lines FL1-FL8 can at least substantially surround thedefined area of feed line FL9. As set forth above, capacitor plates CPare spaced apart from feed lines FL1-FL9. Capacitor plates CP areseparately movable with respect to the feed lines for varying thecapacitance between feed line FL9 and the other feed lines, as describedabove, over a predetermined capacitance range.

FIG. 8A is a top view of a MEMS variable capacitor system generallydesignated 800 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 8A, system 800 can include variable capacitors generally designated802, 804, 806, and 808. System 800 can include cantilever-type variablecapacitors 810-824 positioned over feed lines FL1-FL9. In particular,capacitive plate CP of variable capacitor 810 is positioned over feedlines FL2 and FL9. Capacitive plate CP of variable capacitor 812 ispositioned over feed lines FL1 and FL9. The capacitive plates can bespaced apart from the feed lines in an at least substantiallyperpendicular direction with respect to substrate surface SS. Feed lineFL9 can be connected to feed pad P1. Feed lines FL1 and FL2 can beconnected to feed pad P2. Feed pads P1 and P2 can be connected to asignal line. The capacitive plates can be separately moved byapplication of voltages to variable capacitors 810 and 812 for movementof the variable capacitors such that the capacitances between feed linesFL1 and FL9 and feed lines FL2 and FL9 are selectively varied.

Variable capacitor 804 can include variable capacitors 814 and 816having capacitive plates CP positioned above feed lines FL3, FL4 andFL9. Capacitive plates CP of variable capacitors 814 and 816 can beseparately moved by application of voltages to variable capacitors 814and 816 for movement of components 814 and 816 such that thecapacitances between feed line FL9 and feed lines FL3 and FL4 areselectively varied. Feed lines FL3 and FL4 can be connected to feed padP3. Feed pads P1 and P3 can be connected to a signal line.

Variable capacitor 806 can include variable capacitors 818 and 820having capacitive plates CP positioned above feed lines FL5, FL6 andFL9. Capacitive plates CP of variable capacitors 818 and 820 can beseparately moved by application of voltages to variable capacitors 818and 820 for movement of components 818 and 820 such that thecapacitances between feed line FL9 and feed lines FL5 and FL6 areselectively varied. Feed lines FL5 and FL6 can be connected to feed padP4. Feed pads P1 and P4 can be connected to a signal line.

Variable capacitor 808 can include variable capacitors 822 and 824having capacitive plates CP positioned above feed lines FL7, FL8 andFL9. Capacitive plates CP of variable capacitors 822 and 824 can beseparately moved by application of voltages to variable capacitors 822and 824 for movement of components 822 and 824 such that thecapacitances between feed line FL9 and feed lines FL7 and FL8 areselectively varied. Feed lines FL7 and FL8 can be connected to feed padP5. Feed pads P1 and P5 can be connected to a signal line.

In the example of system 800, feed line FL9 is positioned on a definedarea of substrate surface SS. Feed lines FL1-FL8 are positioned on aplurality of other defined areas of substrate surface SS. The definedareas of feed lines FL1-FL8 substantially surround the defined area offeed line FL9. As set forth above, capacitor plates CP can be spacedapart from feed lines FL1-FL9. Capacitor plates CP are separatelymovable with respect to the feed lines for varying the capacitancebetween feed line FL9 and the other feed lines, as described above, overa predetermined capacitance range.

FIG. 8B is a top view of a MEMS variable capacitor system generallydesignated 826 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. System 826 canbe similar to system 800 shown in FIG. 8A except that the substratesurface area covered by feed line FL9 in FIG. 8B is smaller.

FIG. 9 is a top view of a MEMS variable capacitor system generallydesignated 900 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 9, system 900 can include variable capacitors generally designated902, 904, 906, and 908. System 900 can include cantilever-type variablecapacitors 910 and 912 positioned over feed lines FL1-FL4. Inparticular, capacitive plate CP of variable capacitor 910 can bepositioned over feed lines FL1 and FL3. Capacitive plate CP of variablecapacitor 912 can be positioned overfeed lines FL2 and FL4. Thecapacitive plates can be spaced apart from the feed lines in an at leastsubstantially perpendicular direction with respect to substrate surfaceSS. Feed lines FL1 and FL2 can be connected to feed pad P1. Feed linesFL3 and FL4 can be connected to feed pad P2. Feed pads P1 and P2 can beconnected to a signal line. The capacitive plates can be separatelymoved by application of voltages to variable capacitors 910 and 912 formovement of the variable capacitors such that the capacitances betweenfeed lines FL1/FL2 and feed lines FL3/FL4 are selectively varied.

Variable capacitor 904 can include variable capacitors 914 and 916having capacitive plates CP positioned above feed lines FL4-FL7.Capacitive plates CP of variable capacitors 914 and 916 can beseparately moved by application of voltages to variable capacitors 914and 916 for movement of components 914 and 916 such that thecapacitances between feed lines FL4/FL5 and FL6/FL7 are selectivelyvaried. Feed lines FL5 and FL6 can be connected to feed pad P3. Feedpads P2 and P3 can be connected to a signal line.

Variable capacitor 906 can include variable capacitors 918 and 920having capacitive plates CP positioned above feed lines FL3, FL8, FL9,and FL10. Capacitive plates CP of variable capacitors 918 and 920 can beseparately moved by application of voltages to variable capacitors 918and 920 for movement of components 918 and 920 such that thecapacitances between feed lines FL3/FL8 and FL9/FL10 are selectivelyvaried. Feed lines FL8 and FL9 can be connected to a feed pad P4. Feedlines FL3 and FL10 can be connected to feed pad P2. Feed pads P2 and P4can be connected to a signal line.

Variable capacitor 908 can include variable capacitors 914 and 916having capacitive plates CP positioned above feed lines FL4-FL7.Capacitive plates CP of variable capacitors 914 and 916 can beseparately moved by application of voltages to variable capacitors 914and 916 for movement of components 914 and 916 such that thecapacitances between feed lines FL4/FL5 and FL6/FL7 are selectivelyvaried. Feed lines FL5 and FL6 can be connected to feed pad P3. Feedpads P2 and P3 can be connected to a signal line.

FIG. 10 is a top view of a MEMS variable capacitor system generallydesignated 1000 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 10, system 1000 can include variable capacitors generallydesignated 1002, 1004, 1006, and 1008. Capacitor 1002 can includecantilever-type variable capacitors 1010 and 1012 positioned over feedlines FL1 and FL2. In particular, capacitive plates CP of variablecapacitor 1010 can be positioned over feed lines FL1 and FL2. Capacitiveplate CP of variable capacitor 1012 can be positioned over feed linesFL1 and FL2. The capacitive plates can be spaced apart from the feedlines in an at least substantially perpendicular direction with respectto substrate surface SS. Feed lines FL1 and FL2 can be connected to feedpads P1 and P2. Feed pads P1 and P2 can be connected to a signal line.The capacitive plates can be separately moved by application of voltagesto variable capacitors 1010 and 1012 for movement of the variablecapacitors such that the capacitances between feed lines FL1 and FL2 areselectively varied.

Variable capacitor 1004 can include variable capacitors 1014 and 1016having capacitive plates CP positioned above feed lines FL2 and FL3.Capacitive plates CP of variable capacitors 1014 and 1016 can beseparately moved by application of voltages to variable capacitors 1014and 1016 for movement of components 1014 and 1016 such that thecapacitances between feed lines FL2 and FL3 are selectively varied. Feedline FL3 can be connected to a feed pad P3. Feed pads P2 and P3 can beconnected to a signal line.

Variable capacitor 1006 can include variable capacitors 1018 and 1020having capacitive plates CP positioned above feed lines FL2 and FL3.Capacitive plates CP of variable capacitors 1018 and 1020 can beseparately moved by application of voltages to variable capacitors 1018and 1020 for movement of components 1018 and 1020 such that thecapacitances between feed lines FL2 and FL3 are selectively varied. Feedlines FL2 and FL3 can be connected to feed pad P4. Feed pads P2 and P4can be connected to a signal line.

Variable capacitor 1008 can include variable capacitors 1022 and 1024having capacitive plates CP positioned above feed lines FL2 and FL3.Capacitive plates CP of variable capacitors 1022 and 1024 can beseparately moved by application of voltages to variable capacitors 1022and 1024 for movement of components 1022 and 1024 such that thecapacitances between feed lines FL2 and FL3 are selectively varied. Feedlines FL2 and FL3 can be connected to feed pad P5. Feed pads P2 and P5can be connected to a signal line.

FIG. 11 is a top view of a MEMS variable capacitor system generallydesignated 1100 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 11, system 1100 can include variable capacitors generallydesignated 1102 and 1104. Capacitor 1102 can include cantilever-typevariable capacitors 1106, 1108, 1110, and 1112 positioned over feedlines FL1-FL6. In particular, capacitive plate CP of variable capacitor1106 can be positioned overfeed lines FL1 and FL3. Capacitive plate CPof variable capacitor 1108 can be positioned over feed lines FL1 andFL4. Capacitive plate CP of variable capacitor 1110 can be positionedover feed lines FL2 and FL5. Capacitive plate CP of variable capacitor1112 can be positioned overfeed lines FL2 and FL6. The capacitive platescan be spaced apart from the feed lines in an at least substantiallyperpendicular direction with respect to substrate surface SS. Feed linesFL1 and FL2 can be connected to a feed pad P1. Feed lines FL3-FL6 can beconnected to a feed pad P2. Feed pads P1 and P2 can be connected to asignal line. The capacitive plates can be separately moved byapplication of voltages to variable capacitors 1106-1112 for movement ofthe variable capacitors such that the capacitances between feed pads P1and P2 are selectively varied.

Variable capacitor 1104 can include cantilever-type variable capacitors1114, 1116, 1118, and 1120 positioned overfeed lines FL7-FL12. Inparticular, capacitive plate CP of variable capacitor 1114 can bepositioned overfeed lines FL7 and FL9. Capacitive plate CP of variablecapacitor 1116 can be positioned over feed lines FL7 and FL40.Capacitive plate CP of variable capacitor 1118 can be positioned overfeed lines FL8 and FL11. Capacitive plate CP of variable capacitor 1120can be positioned overfeed lines FL8 and FL12. The capacitive plates canbe spaced apart from the feed lines in an at least substantiallyperpendicular direction with respect to substrate surface SS. Feed linesFL7 and FL8 can be connected to a feed pad P3. Feed lines FL3-FL6 can beconnected to a feed pad P3. Feed pads P1 and P3 can be connected to asignal line. The capacitive plates can be separately moved byapplication of voltages to variable capacitors 1114-1120 for movement ofthe variable capacitors such that the capacitances between feed pads P1and P3 are selectively varied.

FIG. 12 is a top view of a MEMS variable capacitor system generallydesignated 1200 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 12, system 1200 can include cantilever-type variable capacitorsgenerally designated 1202, 1204, 1206, and 1208. Variable capacitor 1202can include variable capacitors VC1 and VC2 positioned above feed linesFL1-FL4. In particular, capacitive plates CP of variable capacitor VC1can be disposed over feed lines FL1 and FL3. Capacitive plates CP ofvariable capacitor VC2 can be disposed over feed lines FL2 and FL4. Thecapacitive plates can be spaced apart from the feed lines in an at leastsubstantially perpendicular direction with respect to substrate surfaceSS. Feed lines FL1 and FL2 can be connected to feed pad P1. Feed linesFL3 and FL4 can be connected to feed pad P2. Feed pads P1 and P2 can beconnected to a signal line. The capacitive plates can be separatelymoved by application of voltages to variable capacitors for movement ofthe variable capacitors such that the capacitances between feed pads P1and P2 are selectively varied.

Variable capacitor 1204 can include variable capacitors VC3 and VC4positioned above feed lines FL3-FL6. In particular, capacitive plates CPof variable capacitor VC3 can be disposed over feed lines FL3 and FL5.Capacitive plates CP of variable capacitor VC4 can be disposed over feedlines FL4 and FL6. The capacitive plates can be spaced apart from thefeed lines in an at least substantially perpendicular direction withrespect to substrate surface SS. Feed lines FL5 and FL6 can be connectedto a feed pad P3. Feed pads P2 and P3 can be connected to a signal line.The capacitive plates can be separately moved by application of voltagesto variable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P2 and P3 are selectively varied.

Variable capacitor 1206 can include variable capacitors VC5 and VC6positioned above feed lines FL5-FL8. In particular, capacitive plates CPof variable capacitor VC5 can be disposed over feed lines FL5 and FL7.Capacitive plates CP of variable capacitor VC7 can be disposed over feedlines FL6 and FL8. The capacitive plates can be spaced apart from thefeed lines in an at least substantially perpendicular direction withrespect to substrate surface SS. Feed lines FL5 and FL6 can be connectedto feed pad P3. Feed lines FL7 and FL8 can be connected to feed pad P4.Feed pads P3 and P4 can be connected to a signal line. The capacitiveplates can be separately moved by application of voltages to variablecapacitors for movement of the variable capacitors such that thecapacitances between feed pads P3 and P4 are selectively varied.

Variable capacitor 1208 can include variable capacitors VC7 and VC8positioned above feed lines FL7-FL10. In particular, capacitive platesCP of variable capacitor VC7 can be disposed over feed lines FL7 andFL9. Capacitive plates CP of variable capacitor VC8 can be disposedoverfeed lines FL8 and FL10. The capacitive plates can be spaced apartfrom the feed lines in an at least substantially perpendicular directionwith respect to substrate surface SS. Feed lines FL7 and FL8 can beconnected to feed pad P4. Feed lines FL9 and FL10 can be connected tofeed pad P5. Feed pads P4 and P5 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P4 and P5 are selectively varied.

FIG. 13 is a top view of a MEMS variable capacitor system generallydesignated 1300 having MEMS variable capacitor variable capacitors andfeed lines according to an embodiment of the subject matter describedherein. Referring to FIG. 13, system 1300 can include cantilever-typevariable capacitors generally designated 1302, 1304, 1306, and 1308.Variable capacitor 1302 can include variable capacitors VC1 and VC2positioned above feed lines FL1-FL4. In particular, capacitive plates CPof variable capacitor VC1 can be disposed over feed lines FL1 and FL3.Capacitive plates CP of variable capacitor VC2 can be disposed over feedlines FL2 and FL4. The capacitive plates can be spaced apart from thefeed lines in an at least substantially perpendicular direction withrespect to substrate surface SS. Feed lines FL1 and FL2 can be connectedto feed pad P1. Feed lines FL3 and FL4 can be connected to feed pad P2.Feed pads P1 and P2 can be connected to a signal line. The capacitiveplates can be separately moved by application of voltages to variablecapacitors for movement of the variable capacitors such that thecapacitances between feed pads P1 and P2 are selectively varied.

Variable capacitor 1304 can include variable capacitors VC3 and VC4positioned above feed lines FL5-FL8. In particular, capacitive plates CPof variable capacitor VC3 can be disposed over feed lines FL5 and FL7.Capacitive plates CP of variable capacitor VC4 can be disposed over feedlines FL6 and FL8. The capacitive plates can be spaced apart from thefeed lines in an at least substantially perpendicular direction withrespect to substrate surface SS. Feed lines FL5 and FL6 can be connectedto feed pad P2. Feed lines FL7 and FL8 can be connected to a feed padP3. Feed pads P2 and P3 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P2 and P3 are selectively varied.

Variable capacitor 1306 can include variable capacitors VC5 and VC6positioned above feed lines FL9-FL12. In particular, capacitive platesCP of variable capacitor VC5 can be disposed over feed lines FL9 andFL11. Capacitive plates CP of variable capacitor VC6 can be disposedoverfeed lines FL10 and FL12. The capacitive plates can be spaced apartfrom the feed lines in an at least substantially perpendicular directionwith respect to substrate surface SS. Feed lines FL9 and FL10 can beconnected to feed pad P3. Feed lines FL1 and FL12 can be connected to afeed pad P4. Feed pads P3 and P4 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P3 and P4 are selectively varied.

Variable capacitor 1308 can include variable capacitors VC7 and VC8positioned above feed lines FL13-FL16. In particular, capacitive platesCP of variable capacitor VC7 can be disposed over feed lines FL13 andFL15. Capacitive plates CP of variable capacitor VC8 can be disposedoverfeed lines FL24 and FL16. The capacitive plates can be spaced apartfrom the feed lines in an at least substantially perpendicular directionwith respect to substrate surface SS. Feed lines FL13 and FL14 can beconnected to feed pad P4. Feed lines FL15 and FL16 can be connected to afeed pad P5. Feed pads P4 and P5 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P4 and P5 are selectively varied.

FIG. 14 is a top view of a MEMS variable capacitor system generallydesignated 1400 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 13, system 1400 can include cantilever-type variable capacitorsgenerally designated 1402, 1404, 1406, and 1408. In this embodiment,capacitive plates CP can be trapezoidal in shape and positioned forminimizing the substrate surface area covered by variable capacitors1402, 1404, 1406, and 1408.

Variable capacitor 1402 can include variable capacitors VC1 and VC2positioned above feed lines FL1-FL4. In particular, capacitive plates CPof variable capacitor VC1 can be disposed over feed lines FL1 and FL3.Capacitive plates CP of variable capacitor VC2 can be disposed over feedlines FL2 and FL4. The capacitive plates can be spaced apart from thefeed lines in an at least substantially perpendicular direction withrespect to substrate surface SS. Feed lines FL1 and FL2 can be connectedto feed pad P1. Feed lines FL3 and FL4 can be connected to feed pad P2.Feed pads P1 and P2 can be connected to a signal line. The capacitiveplates can be separately moved by application of voltages to variablecapacitors for movement of the variable capacitors such that thecapacitances between feed pads P1 and P2 are selectively varied.

Variable capacitor 1404 can include variable capacitors VC3 and VC4positioned above feed lines FL5-FL8. In particular, capacitive plates CPof variable capacitor VC3 can be disposed over feed lines FL5 and FL7.Capacitive plates CP of variable capacitor VC4 can be disposed over feedlines FL6 and FL8. The capacitive plates can be spaced apart from thefeed lines in an at least substantially perpendicular direction withrespect to substrate surface SS. Feed lines FL5 and FL6 can be connectedto feed pad P2. Feed lines FL7 and FL8 can be connected to a feed padP3. Feed pads P2 and P3 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P2 and P3 are selectively varied.

Variable capacitor 1406 can include variable capacitors VC5 and VC6positioned above feed lines FL9-FL12. In particular, capacitive platesCP of variable capacitor VC5 can be disposed over feed lines FL9 andFL11. Capacitive plates CP of variable capacitor VC6 can be disposedoverfeed lines FL10 and FL12. The capacitive plates can be spaced apartfrom the feed lines in an at least substantially perpendicular directionwith respect to substrate surface SS. Feed lines FL9 and FL1 can beconnected to feed pad P3. Feed lines FL11 and FL12 can be connected to afeed pad P4. Feed pads P3 and P4 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P3 and P4 are selectively varied.

Variable capacitor 1408 can include variable capacitors VC7 and VC8positioned above feed lines FL13-FL16. In particular, capacitive platesCP of variable capacitor VC7 can be disposed over feed lines FL13 andFL15. Capacitive plates CP of variable capacitor VC8 can be disposedoverfeed lines FL24 and FL16. The capacitive plates can be spaced apartfrom the feed lines in an at least substantially perpendicular directionwith respect to substrate surface SS. Feed lines FL13 and FL14 can beconnected to feed pad P4. Feed lines FL15 and FL16 can be connected to afeed pad P5. Feed pads P4 and P5 can be connected to a signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitances between feed pads P4 and P5 are selectively varied.

In one embodiment, a MEMS variable capacitor system according to thesubject matter described herein can include a first feed line beingpositioned on a first defined area. Second, third, fourth, and fifthfeed lines can be positioned on a plurality of second defined areas thatsubstantially surround the first defined area. First, second, third, andfourth actuation components can include capacitive plates spaced apartfrom the first feed line. The capacitive plates of the first, second,third, and fourth actuation components can be connected to the second,third, fourth, and fifth feed lines, respectively. Each of thecapacitive plates can be separately movable with respect to the firstfeed line for varying the capacitance between the first feed line andthe respective one of the second, third, fourth, and fifth feed linesover a predetermined capacitance range. An example of this system isprovided in FIG. 15.

FIG. 15 is a top view of a MEMS variable capacitor system generallydesignated 1500 having MEMS variable capacitors and feed lines accordingto an embodiment of the subject matter described herein. Referring toFIG. 15, system 1500 can include cantilever-type variable capacitorsgenerally designated 1502 and 1504. Variable capacitor 1502 can includevariable capacitors 1506, 1508, 1510, and 1512 positioned over feed lineFL1. In particular, capacitive plates CP of variable capacitors 1506,1508, 1510, and 1512 can be positioned over feed line FL1. Capacitiveplates CP of variable capacitors 1506 and 1508 can be connected by asplit feed line FL2 to a feed pad P1. Capacitive plates CP of variablecapacitors 1510 and 1512 can be connected by a split feed line FL3 to afeed pad P2. Feed line FL1 can be connected to a feed pad P3. Feed padsP1 and P2 can be connected to one terminal of a signal line. Feed pad P3can be connected to the other terminal of the signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitance applied to the signal line is selectively varied.

Variable capacitor 1504 can include variable capacitors 1514, 1516,1518, and 1520 positioned overfeed line FL1. In particular, capacitiveplates CP of variable capacitors 1514, 1516, 1518, and 1520 can bepositioned over feed line FL1. Capacitive plates CP of variablecapacitors 1514 and 1516 can be connected by a split feed line FL4 to afeed pad P4. Capacitive plates CP of variable capacitors 1518 and 1520can be connected by a split feed line FL5 to a feed pad P5. Feed pads P4and P5 can be connected to one terminal of a signal line. Feed pad P3can be connected to the other terminal of the signal line. Thecapacitive plates can be separately moved by application of voltages tovariable capacitors for movement of the variable capacitors such thatthe capacitance applied to the signal line is selectively varied.

Shielding

Shielding can be provided within a substrate and positioned for reducingRF interference and/or loss coupled to and/or from the substrate and/orunderlying circuitry. In one embodiment, a MEMS variable capacitor caninclude a substrate having a surface. First and second feed lines canextend on the surface of the substrate. First and second capacitiveplates can be spaced apart from the first and second feed lines. Thefirst and second capacitive plates can be separately movable withrespect to at least one of the first and second feed lines for varyingthe capacitance between the first and second feed lines over apredetermined capacitance range. A shielding material can be positionedwithin the substrate and positioned in an area substantially beneath thefeed lines, feed pads, and capacitive plates for reducing RFinterference and/or loss coupled to/from the substrate and/or underlyingcircuitry.

FIGS. 16A and 16B illustrate a top view and a perspective view,respectively, of a MEMS variable capacitor generally designated 1600having a shielding SH according to an embodiment of the subject matterdescribed herein. Referring to FIGS. 16A and 16B, capacitor 1600 caninclude feed lines FL1 and FL2 connected to feed pads P1-P3. Feed padsP1-P3 can be connected together to a terminal of a signal line. Further,feed lines P4-P6 can be connected to feed pads P4-P6. Feed pads P4-P6can be connected together to the other terminal of the signal line.Capacitive plates CP can be positioned above feed lines FL1 and FL2.Further, capacitive plates CP can be attached to a cantilever-typevariable capacitor or a bridge-type variable capacitor as describedherein for movement of capacitive plates CP with respect to feed linesFL1 and FL2. Capacitive plates CP can be moved individually or togetherfor varying the capacitance applied to the terminals of the signal lineas described herein.

Shield SH can be positioned beneath capacitive plates CP, feed linesFL1-FL6, and feed pads P1-P6. Shield SH can be a ground metal shieldingfor reducing RF interference. Further, shield SH can reduce loss coupledto a lossy substrate, such as a silicon substrate. A similar shield canbe positioned beneath the capacitive plates, feed lines, and feed padsdescribed in the embodiment for reducing RF interference and losscoupled to a substrate. The shielding material can be connected to oneor more feed lines for functioning as a grounded shield. The preciseextent of the shield required will be determined by the substrateproperties, the distance of the feed lines and pads from the substrateand the distance of the shield from the substrate. The shield does notneed to be solid and may have slots or holes.

FIG. 16C illustrates a perspective view of MEMS variable capacitorgenerally designated 1600 having a contouring shielding SH according toan embodiment of the subject matter described herein. Referring to FIG.16C, capacitor 1600 can be contoured to the shape of capacitive platesCP, feed lines FL1-FL6, and feed pads P1-P6.

Simulation Result Graphs

Simulations were performed of some of the MEMS variable capacitors andvariable capacitor systems described herein. The simulations wereperformed using computer simulation software available from AnsoftCorporation, of Pittsburgh, Pa.

FIGS. 17A-17E are graphs illustrating simulation results of capacitorsystem 500 shown in FIG. 5. Referring to FIGS. 17A-17E, capacitance andQ obtained by system 500 is shown over a range of frequencies. FIG. 17Ais a baseline simulation of all capacitor bits closed (1 forcapacitance, 2 for Q) and open (3 for capacitance, 4 for Q) without ashield. The closed Q is marginal but the open Q is terrible. FIGS. 17Band 17C compare the results of using a very low loss substrate to thebaseline showing the very high Q and low minimum capacitance achieved.FIG. 17B is for all actuators up, and FIG. 17C is all down. However, useof such a low-loss (high resistivity) substrate is often not practical,especially when integrating with semiconductor-based circuits. In FIGS.17D and 17E, a similar comparison is made between the baseline and amodified feed structure used to reduce losses and parasitic capacitancefor open and closed cases, respectively.

FIGS. 18A-18D are graphs illustrating simulation results of capacitorsystem 600 shown in FIG. 6. Referring to FIGS. 18A-18D, capacitance andQ obtained by system 600 is shown over a range of frequencies. Thesefigures compare the improvement due to the bi-feed over the otherbaseline. FIG. 18A is the minimum capacitance case, and FIG. 18B is theclosed case. FIG. 18B shows the improved Q and higher self-resonantfrequency of this feed. (capacitance is more stable with frequency). InFIG. 18C, the pads are reduced to half area to measure the contributionof the pads to the parasitic capacitance (2×0.03 pF=0.06 pF). FIG. 18Dexamines the effect of modifying the lateral gap between the feed lines.For this set of material and design parameters, larger gaps lead tohigher loss. This implies that the substrate currents are limited by thecapacitance to the substrate. For very resistivity substrates or veryhigh capacitances to the substrate, this trend will be reversed.

FIGS. 19A-19E are graphs illustrating simulation results of capacitorsystem 700 shown in FIG. 7. Referring to FIGS. 19A-19E, capacitance andQ obtained by system 700 is shown over a range of frequencies. FIG. 19Acompares the performance of this design to the baseline for the opencase, and FIG. 19B for the corresponding all-closed case. FIGS. 19C and19D contrast two different simulation assumptions for the capacitorsystem 700 shown in FIG. 7 (maybe we should leave these out . . . ).FIG. 19E shows the all-up and all-down results capacitor system 700shown in FIG. 7 where the feeds have been modified to minimize theparasitic capacitance to the substrate by using metal layers furtherfrom the substrate where possible and minimizing the feed area. Thismostly improves the all-up performance.

FIG. 20 is a graph illustrating simulation results of capacitor system1100 shown in FIG. 11. Referring to FIG. 20, capacitance and Q obtainedby system 1100 is shown over a range of frequencies. This 3 pad feedversion should be compared to the version with results in FIGS. 19A-19E.This will have somewhat worse performance but better area usage.

FIG. 21 is a graph illustrating simulation results of capacitor system1500 shown in FIG. 15. Referring to FIG. 21, capacitance and Q obtainedby system 1500 is shown over a range of frequencies. This is the top-feddevice. This design will take up much less area for the same capacitancethan the versions with floating capacitor electrode. However, it mayhave worse RF performance and may couple more RF to the controlelectrodes and control lines.

FIG. 22 is a graph illustrating simulation results of capacitor system1200 shown in FIG. 12. Referring to FIG. 22, capacitance and Q obtainedby system 1200 is shown over a range of frequencies. These all-open andall-closed results are for feed networks that are more suitable fordense array utilizing cantilever actuators. High ratio and Q results areobtained.

FIGS. 23A and 23B are graphs illustrating simulation results ofcapacitor system 1300 shown in FIG. 13. Referring to FIGS. 23A and 23B,capacitance and Q obtained by system 1300 is shown over a range offrequencies. Showing the improved performance with the improved packingdensity that this diagonal feed design provides compared to FIG. 12.

FIG. 24 is a graph illustrating simulation results of capacitor system1400 shown in FIG. 14. Referring to FIG. 24, capacitance and Q obtainedby system 1400 is shown over a range of frequencies. These figures showimprovement with trapezoidal shaped capacitance plates.

A simulation was performed of MEMS variable capacitor 1600 withshielding at different distances for determining the effect that theshielding has at different distances. In the simulations, shield SH waspositioned at 7.3 and 11.2 μm away from capacitive plates CP, feed linesFL1-FL6, and feed pads P1-P6. Table 1 below shows shielding simulationresults when the shield at these positions.

TABLE 1 Shielding Simulation Results Shield 11.2 μm Away Shield 7.3 μmAway All Caps No Cap All Caps No Cap Activated Activated ActivatedActivated Q 540 51 450 48 (2 GHz) C (pf) 0.34 4.57 0.450 4.70 (2 GHz)

It will be understood that various details of the presently disclosedsubject matter may be changed without departing from the scope of thepresently disclosed subject matter. Furthermore, the foregoingdescription is for the purpose of illustration only, and not for thepurpose of limitation.

1. A micro-electro-mechanical system (MEMS) variable capacitor systemcomprising: first, second, and third feed pads being spaced apart; afirst feed line connected to the first feed pad and extending towardsthe second feed pad; a second feed line connected to the second feed padand extending towards the third feed pad; third and fourth feed linesconnected to the third feed pad and extending towards the first andsecond feed pads, respectively; a first capacitive plate being spacedapart from the first and third feed lines, wherein the first capacitiveplate is movable with respect to at least one of the first and thirdfeed lines for varying the capacitance between the first and third feedlines over a first predetermined capacitance range; and a secondcapacitive plate being spaced apart from the second and fourth feedlines, wherein the second capacitive plate is movable with respect to atleast one of the second and fourth feed lines for varying thecapacitance between the second and fourth feed lines over a secondpredetermined capacitance range.
 2. The MEMS variable capacitor systemof claim 1 wherein the feed lines are between about 10 μm to about 200μm wide.
 3. The MEMS variable capacitor system of claim 1 wherein thefeed lines are spaced by about 5 μm to about 50 μm.
 4. The MEMS variablecapacitor system of claim 1 wherein the capacitive plates aresubstantially trapezoidal in shape.
 5. The MEMS variable capacitorsystem of claim 1 comprising a substrate, wherein the feed lines areattached to a surface of the substrate.
 6. The MEMS variable capacitorsystem of claim 1 comprising a substrate, wherein the feed lines arepositioned within the substrate.
 7. The MEMS variable capacitor systemof claim 1 comprising first and second actuation components, wherein thefirst actuation component is movable with respect to the at least one ofthe first and third feed lines, wherein the second actuation componentis movable with respect to the at least one of the second and fourthfeed lines, wherein the first and second capacitive plates are attachedto the first and second capacitive plates, respectively.
 8. The MEMSvariable capacitor system of claim 7 wherein each of the actuationcomponents is stationary at one end with respect to the feed lines, andwherein the actuation component is movable along a direction at leastsubstantially parallel to the first and second feed lines.
 9. The MEMSvariable capacitor system of claim 7 wherein each of the actuationcomponents includes two ends that are stationary with respect to thefeed lines, and wherein the actuation component is movable along adirection substantially parallel to the first and second feed lines. 10.The MEMS variable capacitor system of claim 7 wherein each of theactuation components comprises: first and second actuation electrodesbeing spaced apart, wherein at least one of the actuation electrodes ismovable with respect to the other actuation electrode; and a movablecomponent attached to the at least one of the actuation electrodes,wherein the movable component comprises a movable end and a stationaryend, wherein the movable end is movable upon application of a voltageacross the first and second actuation electrodes.
 11. The MEMS variablecapacitor system of claim 7 wherein each of the actuation componentscomprises: first and second actuation electrodes being spaced apart,wherein at least one of the actuation electrodes is movable with respectto the other actuation electrode; and a movable component attached tothe first actuation electrode, wherein the movable component comprises amovable portion and first and second stationary ends, wherein themovable portion is movable upon application of a voltage across thefirst and second actuation electrodes.